To be sure we waste a great deal of water in the landscape because most people just don't understand plants and how they use water.
Plants are not like people. They do not need, nor do they like, frequent water.
Saving 25% in the landscape is the low end of savings in the typical landscape in San Diego.
The short course. Here is how it is done.
The typical irrigation system in any landscape covers the "zones" of different plantings in a landscape.
As an example landscape lets say it has 5 zones set at 5 minutes of water and waters 3 times a week on the irrigation timer.
that is a total weekly watering of 75 minutes of irrigating per week.
now lets look at the zones.
zone 1. lawn
zone 2. established hedge
zone 3 veggie garden
zone 4. established fruit trees
zone 5. established shade trees
Zone 1 and 3, the lawn and veggies, need water frequently, so there is little savings to be had in those zones without eliminating those plantings
zones 2,4 and 5, the hedge, the fruit trees and the shade trees are where the savings are.
these zones should be eliminated from the weekly irrigation timer. Instead they should be put on the "b" program (most clocks have at least 2 programs) with no water days programmed in.
For these zones they should be programmed for 10 minutes and run manually once every 2 to 3 weeks depending on the weather.
Understand that the established hedge and shade trees have extensive root systems, are very efficient at storing water and are probably getting plenty from the lawn water already if their roots extend there.
In the case of the fruit trees the frequent water is screwing up the balance of acidity/sugar in the fruit. That error is a cultural one.
Obviously this example is simplistic as there are other variables(such as equipment efficiency) but under this example the weekly water usage (if zones 2,4 and 5 are done every 2 weeks) works out to
zone 1 15 minutes
zone 2 5 minutes
zone 3 15 minutes
zone 4 5 minutes
zone 5 5 minutes
total average weekly water usage 45 minutes or a savings of 40%
